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Masuda, Yuka*; Sakata, Shiomi*; Kayahara, Saori*; Irie, Natsumi*; Kofu, Maiko; Kono, Yohei*; Sakakibara, Toshiro*; Horii, Yoji*; Kajiwara, Takashi*
Journal of Physical Chemistry C, 127(6), p.3295 - 3306, 2023/02
Oda, Yasuhisa; Oshima, Katsumi; Nakamoto, Takashi*; Hashimoto, Yasunori*; Yamamoto, Tsuyoshi; Hayashi, Kazuo*; Ikeda, Yukiharu; Ikeda, Ryosuke; Kajiwara, Ken; Takahashi, Koji; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 90(7), p.365 - 373, 2014/07
no abstracts in English
Uchida, Kenichi*; Nonaka, Tatsumi*; Kikkawa, Takashi*; Kajiwara, Yosuke*; Saito, Eiji
Physical Review B, 87(10), p.104412_1 - 104412_6, 2013/03
Times Cited Count:97 Percentile:94.71(Materials Science, Multidisciplinary)The longitudinal spin Seebeck effect (LSSE) is investigated in various garnet ferritesYFeO ( = Gd, Ca; = Al, Mn, V, In, Zr) by means of the inverse spin Hall effect in Pt films. The magnitude of the LSSE voltage in the Pt/YFeO samples is found to be enhanced with increasing concentration of Fe in the garnet ferrites, which can be explained by a change in the spin-mixing conductance at the Pt/YFeO interfaces. We also investigate the dependence of the LSSE voltage on macroscopic magnetic parameters of YFeO. The experimental results show that the LSSE voltage in the Pt/YFeO samples hasa positive correlation with the Curie temperature and the saturation magnetization, but no clear correlation with the gyromagnetic ratio and the Gilbert damping constant of the samples.
Kirihara, Akihiro*; Uchida, Kenichi*; Kajiwara, Yosuke*; Ishida, Masahiko*; Nakamura, Yasunobu*; Manako, Takashi*; Saito, Eiji; Yorozu, Shinichi*
Nature Materials, 11(8), p.686 - 689, 2012/08
Times Cited Count:236 Percentile:98.6(Chemistry, Physical)Maekawa, Takashi*; Ide, Shunsuke; Kajiwara, Ken; Nagasaki, Kazunobu*; Isayama, Akihiko; Hada, Kazuyoshi*
Purazuma, Kaku Yugo Gakkai-Shi, 87(10), p.671 - 681, 2011/10
no abstracts in English
Kobayashi, Takayuki; Terakado, Masayuki; Sato, Fumiaki; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Sawahata, Masayuki; Suzuki, Sadaaki; Hiranai, Shinichi; Igarashi, Koichi; et al.
Plasma and Fusion Research (Internet), 4, p.037_1 - 037_10, 2009/08
Electron cyclotron (EC) heating and current drive (CD) are key tools to control fusion plasma especially for effective electron heating and for suppression of neoclassical tearing mode (NTM). Recently, developments of a high power gyrotron and a power modulation technique have been successfully achieved on JT-60U ECRF system in order to enhance the system performance. Stable gyrotron oscillation with oscillation power of 1.5 MW for 1 s was demonstrated in 2007, for the first time. Then temperature rise of cavity and collector has been investigated. It has been shown that the longer pulse operation with 1.5 MW by an improved 110 GHz gyrotron is possible. In addition, modulated ECCD in synchronized with NTM rotation has been performed with the oscillation power of 0.8 MW and the frequency around 5 kHz. The synchronizing system has worked very well and it has played an essential role in NTM suppression experiments on JT-60U.
Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Terakado, Masayuki; Sawahata, Masayuki; Suzuki, Sadaaki; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Hiranai, Shinichi; et al.
Nuclear Fusion, 49(8), p.085001_1 - 085001_7, 2009/07
Times Cited Count:20 Percentile:61.88(Physics, Fluids & Plasmas)In the gyrotron development in JT-60U ECRF system, output power of 1.5 MW for 1 s has been achieved at 110 GHz. It is the world highest power oscillation 1 s. In addition to the carefully designed cavity and collector in view of thermal stress, an RF shield for the adjustment bellows, and a low-dielectric-loss DC break enabled this achievement. Power modulation technique by anode voltage control was improved to obtain high modulation frequency and 5 kHz has been achieved for NTM stabilizing experiments. Long pulse demonstration of 0.4 MW, 30 s injection to the plasma has been achieved with real time control of anode/cathode-heater. It has been confirmed that the temperature of cooled components were saturated and no evidence of damage were found. An innovative antenna having wide range of beam steering capability with linearly-moving-mirror concept has been designed for long pulse. Beam profile and mechanical strength analyses shows the feasibility of the antenna.
Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Terakado, Masayuki; Sawahata, Masayuki; Suzuki, Sadaaki; Yokokura, Kenji; Shimono, Mitsugu; Hasegawa, Koichi; Hiranai, Shinichi; et al.
Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10
In the gyrotron development in JT-60U ECRF system, output power of 1.5 MW for 1 s has been achieved at 110 GHz. It is the world highest power oscillation 1 s. In addition to the carefully designed cavity and collector in view of thermal stress, an RF shield for the adjustment bellows, and a low-dielectric-loss DC break enabled this achievement. Power modulation technique by anode voltage control was improved to obtain high modulation frequency and 5 kHz has been achieved for NTM stabilizing experiments. Long pulse demonstration of 0.4 MW, 30 s injection to the plasma has been achieved with real time control of anode/cathode-heater. It has been confirmed that the temperature of cooled components were saturated and no evidence of damage were found. An innovative antenna having wide range of beam steering capability with linearly-moving-mirror concept has been designed for long pulse. Beam profile and mechanical strength analyses shows the feasibility of the antenna.
Suzuki, Takahiro; Ide, Shunsuke; Hamamatsu, Kiyotaka; Isayama, Akihiko; Fujita, Takaaki; Petty, C. C.*; Ikeda, Yoshitaka; Kajiwara, Ken*; Naito, Osamu; Seki, Masami; et al.
Nuclear Fusion, 44(7), p.699 - 708, 2004/05
Times Cited Count:31 Percentile:69.28(Physics, Fluids & Plasmas)no abstracts in English
Ikeda, Ryosuke; Kajiwara, Ken; Oda, Yasuhisa; Takahashi, Koji; Aoki, Takashi; Oshima, Katsumi; Tsubota, Naoaki; Kobayashi, Takayuki; Moriyama, Shinichi; Sakamoto, Keishi
no journal, ,
no abstracts in English
Hitomi, Takashi*; Kajiwara, Kentaro*; Sugiyama, Takafumi*; Sato, Toshinori
no journal, ,
As a part of research and development of high-level radioactive waste disposal, the effect upon rocks of grouting materials, which are used lining of galleries and water stopping, are studied. Non-destructive integrated CT-XRD method was developed, that is consist of X-ray CT observation and X-ray diffraction of test pieces using X-ray source of large scale synchrotron radiation facility. This report described the effectiveness of this observation method that is applied to observation of constitution minerals of the rock and the grout about a crack part of the granite which was injected grout materials.
Ikeda, Ryosuke; Oda, Yasuhisa; Kajiwara, Ken; Terakado, Masayuki; Aoki, Takashi; Oshima, Katsumi; Tsubota, Naoaki; Hayashibara, Masashi; Hayashi, Kazuo*; Kobayashi, Takayuki; et al.
no journal, ,
no abstracts in English
Kofu, Maiko; Kajiwara, Takashi*; Kawamura, Seiko; Kikuchi, Tatsuya*; Nakajima, Kenji; Matsuura, Masato*; Shibata, Kaoru; Nagao, Michihiro*; Yamamuro, Osamu*
no journal, ,
no abstracts in English